Elevated groundwater phosphorus concentrations across a vulnerable agricultural region
Year: 2026
Type: article
Abstract: Water quality degradation through the generation of harmful algal blooms (HABs) from excess nutrient inputs like nitrogen (N) and phosphorus (P) is a common issue worldwide. Traditionally, N and P are considered when monitoring nutrient pollution of surface water while only N (commonly nitrate) is considered for groundwater since P concentrations are considered too low to be significant. However, recent studies have identified groundwater P concentrations over 0.1 mg-P/L, a concentration that poses an increased risk of eutrophication in surface waters, in shallow groundwater that could be transported to surface water through groundwater seeps or hyporheic zone mixing. Given the health impacts and economic consequences of HABs, an examination of the occurrence and distribution of P in groundwater is necessary to protect public and ecosystem health. Here we examine the distribution of groundwater P in relationship to groundwater nitrate in the agrarian state of Nebraska, United States from both monitoring and irrigation wells. Overall, concentrations of groundwater P were higher in the eastern part of the study area than the west. Median concentrations from irrigation and monitoring wells were near or above 0.1 mg-P/L. Similarly, both shallow (<30m) and deep (>30m) wells had groundwater P concentrations above 0.1 mg-P/L. Groundwater pH was inversely correlated with groundwater P, but no other strong correlations between P and other geochemical parameters was observed.Concentrations of groundwater P above 0.1 mg-P/L can co-occur with areas with groundwater nitrate concentrations above 3 mg-N/L with these areas commonly showing signs of elevated agricultural intensity such as high corn yield, high cattle number, and high fertilizer application. However, areas with groundwater P above 0.1 mg-P/L and nitrate concentrations below 3 mg-N/L commonly show characteristics of low agricultural intensity. Overall, this work highlights the importance of considering groundwater P in regional nutrient studies.
Source: Environmental Research Water
Authors: Jeffrey P Westrop, Jessica R Corman
Institution: University of Nebraska–Lincoln
Language: English
Subfield: Environmental Chemistry
Field: Environmental Science
Domain: Physical Sciences
Open Access status: gold
Estimated APC paid: $2,515
OpenAlex ID: W7162750852